Device for damping the recoil of a tool connected to a hammer machine

ABSTRACT

A recoil damping device for a hammer machine in which a heavily prestressed spring is used, the spring being mounting between two supporting surfaces in the machine housing. The tool acts on the spring between the supporting surfaces. These characteristics give as a result that the length of the spring is not influenced by the feeding force.

United States Patent [191 Eldiif et al.

[ 1 Nov. 11, 1975 DEVICE FOR DAMPING THE RECOIL OF A TOOL CONNECTED TO AHAMMER MACHINE lnventors: Ake Torsten Ekliif, Skarholmen;

Gunnar Vigg Riss Romell, Djursholm, both of Sweden [56] References CitedUNITED STATES PATENTS 2.292.867 8/1942 Charles 173/139 X 2,609,8138/1952 Maurer et a1. 173/139 X 2,638,749 5/1953 Sparano 173/139 X3,086,501 4/1963 Nielsen 173/139 X 3,114,421 12/1963 McCloud 173/139 X3,666,024 5/1972 Beaumont 173/105 Prinzm E.\"aminer-l-lenry C.Sutherland Assistant Eraminer-Richard E. Favreau Attorney, Agent, orFirm-Flynn & Frishauf [57] ABSTRACT A recoil damping device for a hammermachine in which a heavily prestressed spring is used, the spring beingmounting between two supporting surfaces in the machine housing. Thetool acts on the spring between the supporting surfaces. Thesecharacteristics give as a result that the length of the spring is notinfluenced by the feeding force.

8 Claims, 1 Drawing Figure US. Patent Nov. 11, 1975 DEVICE FOR DAMPINGTHE RECOIL OF A TOOL CONNECTED A HAMMER MACHINE BACKGROUND The presentinvention relates to hammer machines and concerns a device for dampingthe recoil of a tool connected to the machine.

A known device of this kind comprises a spring through which feedingforce is transferred from the ma chine housing to the tool. That devicehas the disadvantage that the length of the spring is dependent on theapplied feeding force. This means that the position in which the shankof the tool is situated when the hammer piston hits the shank isdependent on the applied feeding force. A machine which comprises arecoil damper of that kind works optimally only together with a certainpredetermined feeding force.

SUMMARY OF THE INVENTION The present invention aims at doing away withthe above mentioned disadvantage. This is achieved in that a spring isprestressed in the machine housing between two supporting surfacesarranged at a fixed axial distance. Since the spring is prestressed inthe machine housing, an applied feeding force results therein that onlya part of the force of the spring acting on the machine housing istransferred to the tool. This means that the stress in the spring andconsequently the length of the spring is unchanged.

BRIEF DESCRIPTION OF THE DRAWING An embodiment of the invention isdescribed below with reference to the accompanying drawing which shows ahammer drilling machine partly in section.

Detailed Description of Illustrated Embodiment The hammer drillingmachine shown in the FIGURE comprises a machine housing 1 in which aforwards and backwards movable hammer piston 3 is arranged. Adrill-sleeve 6 is by means of rolling bearings 8, 9 journalled in themachine housing 1. A motor 2 rotates via a toothed wheel 5, thedrill-sleeve 6, and a further sleeve 7 a tool 4 which is axially movablein the machine. The rolling bearing 8 rests against a supporting surface13 arranged in the machine housing 1. A rolling bearing 10 rests againsta supporting surface 14, which is arranged at a fixed axial distancefrom the surface 13, in the machine housing 1. A transferring devicerests with a surface 16 against the tool 4 and is pressed forwards by aprestressed spring 12 which via a sleeve 11 rests against the bearing10.

The machine shown works in the following way. When there is no feedingforce applied, the force from the prestressed spring 12 is transferredvia the transferring device 15, the drill-sleeve 6, and the bearing 8 tothe supporting surface 13 of the machine housing 1. When feeding forceis applied to the machine housing 1 the tool 4 is pressed against thesurface 16 on the transferring device 15. This does not mean that thestress in the spring is changed but only that the supporting surface 13is unloaded. During drilling the tool 4 is turned by means of the motor2 at the same time as it is exposed to impacts from the hammer piston 3.When the tool 4 recoils from the material in which drilling occurs ithits the surface 16 on the transferring device 15 which through this islifted out of contact with the drillsleeve 6 if the recoil force exceedsa certain value.

Through this the influence of the recoil on the machine housing 1 isdamped. The tool 4 is then returned to-.the

position which is independent of the feeding force by the spring 12. i

The above described and illustrated embodiment of the invention is onlyto be regarded as an example which can be modified within the scope ofthe subsequent claims.

What we claim is:

l. A recoil damping device for a hammer-type rockdrilling machine whichincludes a tool, a machine housing coupled to said tool andsubstantially constantly applying a feeding force to said tool in aworking direction, means for additionally supplying impacts to said tooland means for rotating said tool, said tool recoiling after applicationof said impacts, said recoil damping device damping the recoil of saidtool and comprising:

a spring coupled to said machine housing for transferring said feedingforce from said machine housing to said tool;

two supporting surfaces in said machine housing and arranged with afixed relative spacing therebetween in the direction of said feedingforce;

two rolling bearings each resting against a respective one of saidsupporting surfaces;

said tool being coupled to said machine housing so as to act on saidspring between said rolling bearings; and

said spring being dimensioned and heavily prestressed between saidrolling bearings so that the length of said spring is substantially notinfluenced by said feeding force applied to said tool.

2. A device according to claim 1 wherein said rolling bearings compriseball bearings.

3. A device according to claim 1 in which said means for rotating thetool is arranged between said spring and one of said rolling bearings,and wherein a further rolling bearing is provided, said tool rotatingmeans being carried in the machine housing by said one rolling bearingand said further rolling bearing.

4. A device according to claim 2 comprising means for transferringfeeding force, which transferring means partly rests against the springand partly against the tool.

5. A hammer-type rock-drilling machine comprising:

a tool;

a machine housing coupled to said tool and including means forsubstantially constantly applying a feeding force to said tool in aworking direction, means for additionally supplying impacts to said tooland means for rotating said tool, said tool recoiling after applicationof said impacts; and

a recoil clamping device damping the recoil of said tool and comprising:

a spring coupled to said machine housing for transferring said feedingforce from said machine housing to said tool;

two supporting surfaces in said machine housing and arranged with afixed relative spacing therebetween in the direction of said feedingforce;

two rolling bearings each resting against a respective one of saidsupporting surfaces;

said tool being coupled to said machine housing so as to act on saidspring between said rolling bearings; and

said spring being dimensioned and heavily prestressed between saidrolling bearings so that the length of said spring is substantially notinfluenced 4 being carried in the machine housing by said one rollingbearing and said further rolling bearing.

8. A device according to claim 7 comprising means for transferringfeeding force, which transferring means partly rests against the springand partly against the tool.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO.3,918,535 DATED November 1 1 1 975 lNVENTOR(S) Ake Torsten EKLOF et alIt is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

In the heading of the patent, change priority data to read:

May 23 1973 Sweden .7307224-1--;

In the Abstract, line 3 change "mounting" to -mounted.

Signed and Scaled this seventeenth D ay Of February 1 9 76 [SEAL] A ttest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ojParentsand Trademarks

1. A recoil damping device for a hammer-type rock-drilling machine whichincludes a tool, a machine housing coupled to said tool andsubstantially constantly applying a feeding force to said tool in aworking direction, means for additionally supplying impacts to said tooland means for rotating said tool, said tool recoiling after applicationof said impacts, said recoil damping device damping the recoil of saidtool and comprising: a spring coupled to said machine housing fortransferring said feeding force from said machine housing to said tool;two supporting surfaces in said machine housing and arranged with afixed relative spacing therebetween in the direction of said feedingforce; two rolling bearings each resting against a respective one ofsaid supporting surfaces; said tool being coupled to said machinehousing so as to act on said spring between said rolling bearings; andsaid spring being dimensioned and heavily prestressed between saidrolling bearings so that the length of said spring is substantially notinfluenced by said feeding force applied to said tool.
 2. A deviceaccording to claim 1 wherein said rolling bearings comprise ballbearings.
 3. A device according to claim 1 in which said means forrotating the tool is arranged between said spring and one of saidrolling bearings, and wherein a further rolling bearing is provided,said tool rotating means being carried in the machine housing by saidone rolling bearing and said further rolling bearing.
 4. A deviceaccording to claim 2 comprising means for transferring feeding force,which transferring means partly rests against the spring and partlyagainst the tool.
 5. A hammer-type rock-drilling machine comprising: atool; a machine housing coupled to said tool and including means forsubstantially constantly applying a feeding force to said tool in aworking direction, means for additionally supplying impacts to said tooland means for rotating said tool, said tool recoiling after applicationof said impacts; and a recoil damping device damping the recoil of saidtool and comprising: a spring coupled to said machine housing fortransferring said feeding force from said machine housing to said tool;two supporting surfaces in said machine housing and arranged with afixed relative spacing therebetween in the direction of said feedingforce; two rolling bearings each resting against a respective one ofsaid supporting surfaces; said tool being coupled to said machinehousing so as to act on said spring between said rolling bearings; andsaid spring being dimensioned and heavily prestressed between saidrolling bearings so that the length of said spring is substantially notinfluenced by said feeding force applied to said tool.
 6. A deviceaccording to claim 5 wherein said rolling bearings comprise ballbearings.
 7. A device according to claim 5 in which said means forrotating the tool is arranged between said spring and one of saidrolling bearings and wherein a further rolling bearing is provided, saidtool rotating means being carried in the machine housing by said onerolling bearing and said further rolling bearing.
 8. A device accordingto claim 7 comprising means for transferring feeding force, whichtransferring means partly rests against the spring and partly againstthe tool.